1. Field of the Invention
The present invention relates to an electromagnetic switch for a starter motor used for vehicles or the like. More particularly, it relates to a connecting terminal attached to a B-terminal bolt of the electromagnetic switch.
2. Discussion of Background
FIG. 3 is a longitudinal cross-sectional view of a conventional electromagnetic switch for a starter motor, wherein reference numeral 1 designates an exciting coil wound on a bobbin 2, numeral 3 designates a fixed iron core for supporting an end of the bobbin 2, numeral 4 designates a casing which forms a yoke and is firmly attached with the fixed iron core 3, numeral 5 designates a plunger supported movably in the axial direction along the inner circumferential portion of the front end part of the casing 4, the plunger being made of a magnetic material so as to form a movable iron core, numeral 6 designates a return spring for the plunger 5, and numeral 8 designates a hook having its rear half portion inserted in the hole of the plunger 5 so as to be movable in the axial direction of it, the hook being made of a material such as a resin-molded material and having its front end portion with which the upper end portion of a shift lever (not shown) is engaged so that the shift lever is turned by a reciprocal movement of the hook 8.
Numeral 9 designates a compression spring for urging the hook 8 backwardly.
Numeral 10 designates a rod held in the central bore of the fixed iron core 3 so as to be movable in the axial direction, numeral 11 designates an insulating sleeve fitted to the rod 10, numeral 12 designates a movable contact fitted to the insulating sleeve 11, which is made immovable by a snap ring 14 by interposing an insulating sheet plate 13 therebetween, numeral 15 designates a compression spring exerting an urging force to the movable contact 12, numeral 16 designates an insulating cap placed in contact with the rear end of the fixed iron core 3 and firmly fixed to the casing 4 by means of caulking, and numeral 17 designates a return spring for the rod 10.
Numeral 18 designates one of fixed contacts opposing the movable contact 12. An M-terminal bolt 19 is formed integrally with the fixed contact so as to extend in parallel to the axial center line of the exciting coil 1. A connecting line to a motor is connected to the M-terminal bolt. Numeral 20 designates the other fixed contact opposing to the movable contact. A B-terminal bolt 21 is formed integrally with the other fixed contact so as to extend in parallel to the axial center line of the exciting coil 1. Numerals 22 designate toothed lock washers engaged with the terminal bolts 19, 21.
A connecting terminal 24 is connected to the B-terminal bolt 21 by fastening a nut 23. Numeral 25 designates a surround insulating body, made of a resin-molded material, in which a part of the connecting terminal 24 is embedded. A connecting wire is connected between the connecting terminal 24 and a battery (not shown). Numeral 26 is an insulating cover plate fitted to the surrounding portion of the surrounding insulation body 25 which surrounds the B-terminal bolt 21. The connecting terminal 24 is used when the connecting wire from the battery is drawn in a specified direction. The connecting terminal 24 is provided with at its one end side a contacting sheet portion 24a. The other end side of the connecting terminal 24 is provided with a threaded portion 24b and a flange portion 24c.
As shown in the front view of FIG. 4A, the connecting terminal 24 is extended to the direction of an angle .theta. with respect to a diametrical line Y--Y of the insulating cap 16. Numeral 16a designates a projection formed at the center of an outer edge portion of the insulating cap 16. Numeral 27 designates an S-terminal connected to a lead wire for the exciting coil 1. The S-terminal is connected with a connecting wire from a key switch.
Numeral 28 is a connecting piece for connecting the M-terminal bolt 19 with a lead wire extending from the other end of a current coil in the exciting coil 1, wherein the lead wire is connected to the connecting piece 28 at a soldering potion 29.
It is necessary to determine the position of the connecting terminal 24 to the insulating cap 16 so as to extend at a specified angle. For this, the arrangement is made as shown in FIG. 4B which shows a front sectional view. Namely, the bottom portion 24d of the contacting seat portion 24a which is opposite the threaded portion of the connecting terminal 24 is made flat so as to be parallel to the side surface of the projection 16a of the insulating cap 16. The contacting seat portion 24a is covered by molding a resinous material to form the surrounding insulation body 25 except that both end portions 24e of the bottom portion 24d are exposed from the surrounding insulating body 25 so that the both end portions as turn-prohibiting projections are exposed out of the resinous material. The connecting terminal 24 is fitted to the B-terminal bolt 21 while the turn-prohibiting portions 24e are in contact with the side surface of the projection 16a. Then, the nut is fastened to the threaded portion, whereby the connecting terminal 24 is fixed to the B-terminal bolt 21 at a specified angle .theta..
The operation of the conventional electromagnetic switch will be described. When a current is supplied to the exciting coil 1, the plunger 5 is attracted toward the fixed iron core 3. Then, the hook 8 is retracted to turn the shift lever, whereby the movable contact 12 is brought to the pair of fixed contacts 18, 20 to thereby start the starter motor.
Thus, in the conventional electromagnetic switch, the position of the connecting terminal 24 is determined to direct at a specified angle .theta. by contacting the turn-prohibiting portions 24e at exposed ends of the bottom portion 24d of the connecting seat portion 24a to the side surface of the projection 16a. However, the conventional electromagnetic switch had the following problem. When the angular direction of drawing the connecting terminal was changed, it was necessary to prepare a new connecting terminal having a specified angle position, and thereafter, surrounding insulation body was formed by molding in which the connecting terminal was embedded.